Labor Flashcards
the physiologic process by which a fetus is expelled form the uterus
Labor
what brings about demonstrable effacement and dilatation of the cervix during labor
Uterine contractions
how open the internal os is
dilation
what measurement is considered complete dilation?
10 cm
length of the cervix (how thick it is)
Difference between the internal and external cervical os
Effacement
- degree of descent of the presenting part of the fetus
- Measured in cm from the ischial spines
- Can measure it in thirds
station
consistency types of cervix to dx labor?
Soft, medium or firm
More firm means they are not in labor
positions of cervix for dx of labor
Anterior, mid position or posterior
In order to diagnosis labor, there MUST BE ?
cervical change
Contractions without cervical change could represent false labor are called?
Braxton Hicks contractions
what scoring determines how favorable the cervix is for labor
Bishop score
Score >8 = favorable cervix for labor
Howto check the status of membranes (4) to dx labor?
- Ferning
- Nitrazine
- Presence of pooling
- AFI
the rupture of membranes during labor
Spontaneous rupture of membranes
the rupture of membranes before the onset of labor
Premature rupture of membranes
Major pathogen in neonatal sepsis
group B strep
how to screen group B strep
> 35 weeks all pregnant women have ano-vaginal swab
tx for positive group B strep
Treatment in labor - PCN
- If allergic - obtain sensitivities usually use Erythromycin or Clindamycin
- If allergic to penicillin and don’t have sensitivities = Vancomycin
- Try to avoid if possible
- Can cause nonreassuring fetal status and fetal respiratory depression
IV pain meds
MC pain management in labor
Regional Anesthesia - Epidural Anesthesia
- Epidural catheter placed in L3-L4 interspace
- Initial bolus of anesthetic given then a continuous infusion started
- Offered to patients having a vaginal delivery
Complications with epidural anesthesia
- Maternal hypotension
- Maternal respiratory depression
- Spinal headache
CI for epidural anesthesia
- Maternal bleeding disorder or use of LMWH within 12h
- Patient refusal
- One time dose placed directly into spinal canal
- Used for cesarean delivery
- Complications and contraindications similar to epidural
Spinal Anesthesia
- Provides perineal anesthesia
- Used with operative vaginal deliveries or for extensive perineal repairs after delivery
Pudendal Block
Used for cesarean delivery in emergent or urgent settings
General Anesthesia
complications of General Anesthesia
during labor
- Maternal aspiration
- Risk of hypoxia to mother and fetus
indications for induction of labor
maternal, fetal or placental reasons
labor induction success is related to Bishop score how?
- Bishop Score < 5 may lead to failed induction 50% of time
- Bishop Score < 5 indicates need for cervical ripening
Prostaglandins MOA for labor induction
Help ripen and dilate the cervix
Cause dissolution of collagen bundles and increase water uptake by cells
2 Prostaglandins used for labor induction
- Cervidil –PGE2, vaginal
- Cytotec – PGE1, vaginal or oral
SE of prostaglandins
- Tachysystole, fever, vomiting, diarrhea
- Uterine rupture
CI of prostaglandins
- History of cesarean section
- myomectomy (peeling tissue from the uterus)
- hysterotomy
Identical version of oxytocin released from posterior pituitary leading to uterine contractions
Pitocin
SE of Pitocin
- Uterine rupture (but not as likely as the prostaglandins)
- Hyponatremia
- Hypotension
- Amniotic fluid embolism
CI of pitocin
- Fetal distress
- hypersensitivity
2 manual/”tool” methods of labor induction
- Balloon catheter (Cook)
- Laminaria - Rolled up seaweed that pulls out water and in turn dilates the cervix
Amnio hook used to puncture amniotic sac can help with what?
labor induction
Intervening to increase the already present contractions?
what medication is used?
Augmentation of Labor
pitocin
types of operative vaginal delivery
- Forceps
- Vacuum – used more often now
indications for operative vaginal delivery
- Prolonged second stage of labor
- Maternal exhaustion
- Hasten delivery for fetal compromise
Abdominal delivery of a fetus
c-section
stages of labor
- From onset of labor to complete cervical dilation
- From complete cervical dilation to expulsion of fetus
- From delivery of infant to delivery of placenta
- From delivery of placenta to one hour postpartum
what is the labor curve (old way)?
Freidman’s curve (1950s)
- Good guideline for expected progression in labor
- Helps determine abnormal labor patterns
what does the new labor curve include?
- Spontaneous labor
- Induced labor
difference between spontaneous and induced labor on labor curve
- Spontaneous labor
- Labor progresses similarly for multips and primips until 6cm
- Defined active phase at 6cm - After 6cm, multips progressed much quicker - Induced labor
- Latent phase of labor is significantly longer in induced labor compared with spontaneous labor - Active phase of labor is similar between the two groups
two phases of the 1st stage of labor
- Latent phase - From onset of labor with slow cervical dilation to ~6 cm; slower phase
- Active phase - From ~6cm to complete dilation (10cm); Faster rate of cervical change
- Nulliparous patient: 1.2cm/h
- Multiparous patient: 1.5cm/h
Factors affecting active stage of labor:
3 P’s
Power – uterus
Passenger – fetus
Pelvis – baby has to fit out of
refers to the force generated by the contractions of the uterine myometrium
Power - uterine contractions
uterine contractons/power activity can be assessed by ?
- observation of the mother
- palpation of the fundus
- external tocodynamometry
Contraction force can also be measured by direct measurement of intrauterine pressure using an internal pressure monitor using?
IUPC – Intrauterine Pressure Catheter
Generally how many contractions in a ___ minute period is considered adequate labor
3-5 contractions
10 min
Adequate labor is how many Montevideo units in 10 min
> 200
Can only measure Montevideo units with IUPC
if < 200 Montevideo units in 10 minutes, what can be given to increase power?
Start pitocin to augment labor
Fetal variables that can affect labor:
- Fetal Lie – longitudinal, transverse or oblique
- Fetal presentation
- Attitude - Degree of flexion or extension of the fetal head
- Position - Relationship between the fetal presenting part to the right or left side of the birth canal
- Station
- Number of fetuses
- Presence of fetal anomalies – hydrocephalus, sacrococcygeal teratoma
fetal in vertex position, what is the reference point (triangle feeling)
occiput
fetal in breech position, what is in reference point
sacrum
what are the different fetal presentations
vertex (head down), breech (butt down), shoulder, compound (something in front of the baby-arm) and funic (umbilical cord)
how to dx of fetal presentation and position
- Leopolds maneuver (abdominal palpation)
- Vaginal examination - Palpation of fetal sutures and fontanels
- Ultrasound
what is the Leopolds maneuver (abdominal palpation)?
- Mother lies supine
- determines: Fetal lie, Estimate fetal wt, Fetal position, Fetal presentation
- Difficult if mother is obese, polyhydramnios or multifetal gestation
indications for c-section
- Any position other than vertex
- Macrosomia - fetus >5k g; if DM mother - 4.5k g
- Small pelvic outlet - Cephalopelvic disproportion
- Active phase arrest of labor
- Prolonged second stage of labor
- Umbilical Cord Prolapse
Small pelvic outlet can result in ?
cephalopelvic disproportion - Passenger is too large for the pelvis; need c-section
no progression in cervical dilation in patients who are at least 6-cm dilated with rupture of membranes despite 4 hours of adequate uterine activity or 6 hours of inadequate uterine activity with oxytocin augmentation
Active phase arrest of labor
Indication for cesarean delivery
more than 3 hours of pushing in nulliparous individuals and 2 hours of pushing in multiparous individuals
Prolonged second stage of labor
Indication for cesarean delivery
RF for Umbilical Cord Prolapse
- Artifical rupture of membranes
- Unengaged fetal head
OBSTETRICAL EMERGENCY! - Indication for cesarean delivery
- Interval between full cervical dilation to delivery of the infant
- Characterized by descent of the presenting part through the maternal pelvis and expulsion of the fetus
2nd stage of labor
Indications of second stage:
- Pelvic/rectal pressure
- Mother has active role of pushing to aid in fetal descent
Examining the fetal head during the second stage may become difficult due to ?
molding - Alteration of the fetal cranial bones to each other as a result of compressive forces of the maternal bony pelvis
Localized edematous area on the fetal scalp caused by pressure on the scalp by the cervix
caput
degrees of perineal lacerations
- First degree - Injury to perineal skin and vaginal mucosa only
- Second degree - Injury to the perineal body
- Third degree - Injury through the external anal sphincter
- Fourth degree - Injury through the rectal mucosa
what is Episiotomy
- Surgical incision of female perineum
- Increases diameter of soft tissue pelvic outlet to allow delivery of a fetus
- ACOG supports restricted use of episiotomy
rationale for episiotomy
- Reduction in third or fourth degree lacerations
- Ease of repair
- Reduction in neonatal trauma
- Reduction in shoulder dystocia
indication for episiotomy
fetal distress
complications of episiotomy
- Increase vaginal bleeding
- Increase postpartum pain
- Unsatisfactory anatomic results
- Sexual dysfunction
- Increase risk of infection
types of episiotomy
- midline
- mediolateral
Difficulty in delivery of the anterior shoulder due to impaction of the anterior shoulder on the pubic symphysis
Shoulder Dystocia
maternal RF for shoulder dystocia
- Fetal macrosomia
- Diabetes – overt and gestational
- Previous shoulder dystocia
- Maternal obesity
- Postterm pregnancy
- Prolonged second stage of labor
- Operative vaginal delivery
Increased morbidity and mortality to mother and fetus
fetal complications of shoulder dystocia
- Fracture of humerus and clavicle
- Brachial plexus injuries
- Phrenic nerve palsy
- Hypoxic brain injury
- Death
how to dx shoulder dystocia
Made when routine delivery maneuvers fail to deliver the anterior shoulder
management for shoulder dystocia
- Call for help
- Episiotomy
- McRoberts maneuver – sharp flexion of maternal hips
- Suprapubic pressure
- Delivery of posterior shoulder
- Other maneuvers – Rubin, Wood’s corkscrew
- Symphisiotomy
- Zavanelli – replace infants head back into the pelvis and do a c-section
Three signs of placental separation:
- Lengthening of umbilical cord
- Gush of blood
- Fundus becomes globular and more anteverted against abdominal hand
Placenta is delivered using what method?
- one hand on umbilical cord with gentle downward traction
- Other hand on abdomen supporting the uterine fundus
Risk factor for aggressive traction is ?
uterine inversion
- Obstetrical emergency!!
- Immediate replacement of fundus required - Manually or surgically
- Refers to the time from delivery of the placenta to 1 hour immediately postpartum
- Blood pressure, uterine blood loss and pulse rate must be monitored closely
4th stage of labor
causes of high risk postpoartum hemorrhage
- Uterine atony – MCC
- Retained placental fragments
- Unrepaired lacerations of vagina, cervix or perineum
how to dx postpartum hemorrhage (how many cc?)
Blood loss >500c in a vaginal delivery or >1000cc in a cesarean delivery
tx for postpartum hemorrhage
- Removal of placental fragments or repair of lacerations
- Additional IV access
- Type and cross match for blood
- Medications for uterine atony: Pitocin, Methergine, Cytotec, Hemabate
Refers to changes in the fetal head position during its passage through the canal.
cardinal movements of labor
7 distinct movements of labor
- Engagement
- Descent
- Flexion
- Internal rotation
- Extension
- External rotation/restitution
- Expulsion
- Passage of the widest diameter fetal presenting part below the plane of the pelvic inlet
- The head is said to be engaged if the leading edge is at the level of the ishial spines.
what movement of labor
engagement
movement of labor - Refers to the downward passage of the presenting part through the bony pelvis
descent
movement of labor - Occurs passively as the head descends due to the shape of the bony pelvis.
flexion
type of flexion that occurs naturally but complete flexion usually occurs only in the labor process
partial
type of flexion that allows the fetal head’s smallest diameter to fit through the pelvis
complete flexion
Smallest diameter = subocciptobregmatic diameter
- Rotation of the fetal head from occiput transverse to occiput anterior or posterior position
- Occurs passively due to the shape of the bony pelvis
internal rotation
- Occurs when the fetus has descended to the level of the vaginal introitus
- When occiput is just past the level of the symphysis, the angle of the birth canal changes to upward position
extension
- As the head is delivered, it rotates back to its original position prior to internal rotation
- Head aligns anatomically with the fetal torso
- The release of the passive forces on the fetal head allows it to return to appropriate position
External Rotation/Restitution
- Delivery of the fetus
- Downward traction allows release of the shoulder and the fetus is delivered
Expulsion
Normal fetal heart rate (FHR) ?
110-160bpm
common causes of fetal bradycardia
- Congenital heart block - Seen in infants whose mothers suffer from SLE
- Maternal hypotension
common causes of fetal tachycardia
- Infection
- Terbutaline
what is considered the baseline of FHR?
Mean bpm over a 10 minute window
what is variability in FHR?
Moment to moment variation from the baseline
The babies HR changes from beat to beat (145, 152, 150, 156, etc.)
4 different types of variability seen in FHR
- Absent - 0 bpm of variation; worrisome
- Minimal - 1-5 bpm of variation; Common when asleep or inactive
- Moderate - considered normal; 5-25 bpm of variation
- Marked - >25 bpm of variation; Worrisome!
when can accelerations be seen in FHR
weeks
- > 32 weeks: at least 15bpm and lasting 15s
- < 32 weeks: at least 10bpm and lasting 10s
- these can be normal (they go away after contraction)
- Begin and end approximately at the same time as contractions
- Result of head compression
- No intervention required
what type of decelerations
Early decelerations
- Begin at peak of contraction and slowly return to baseline after the contraction has finished
- Result of uteroplacental insufficiency (not enough reserve to keep the babies HR up during the contraction)
- requires intervention
what type od deceleration
late decelerations
interventions for late decelerations
- Position, Oxygen, Stop Pitocin, Check cervix, Fluid Bolus
- Consider assisted delivery or cesarean delivery with more than 50% of the contractions
- Can occur at anytime
- Drop more precipitously
- Result of cord compression
- Intervention may be necessary
what type of deceleration
Variable decelerations
possible intervention for variable decelerations
Amnioinfusion – infusion of saline into amniotic sac
Smooth sine wave in FHR, what is this waveform
Sinusoidal waveform
common cause of Sinusoidal waveform
fetal anemia
category I of FHR tracings
- baseline FHR 110-160
- moderate FHR variability
- absence of late or variable decelerations
- accelerations maybe present or absent
Category II of FHR tracings
- includes all EFHRT not categorized as category I or III
category III FHR tracings
- absent FHR variability with any of the following:
- recurrent late decelerations
- recurrent variable decelerations
- bradycardia - sinusoidal pattern
Evaluates the fetal response to a transient reduction in fetal oxygen delivery during uterine contractions
contraction stress test
use what to achieve 3 contractions in 10 mins?
pitocin
indications for contraction stress test
Evaluate fetal status before induction of labor
interpretations for contraction stress test
- Positive – BAD – C-section! - Nonreassuring fetal heart tracing
- With 50% or greater of contractions, a late deceleration is occurring - Equivocal – Wait and See
- Nonpersistent late decelerations - Negative – Good to Go
- Reassuring fetal heart tracing
